84 THE ODD RED SANDSTONE AT SODTHALL. [March I913, 



An important feature of the Devonian rocks below the Thames 

 Valley was that all the three fossiliferous localities were of Upper 

 Devonian age : this might have been expected. The Upper 

 Devonian rocks of West Somerset were believed by the speaker 

 to overlap the Devonian rocks below them, and in the Mendips and 

 at Tortworth the Upper Old Red Sandstone rested on the Silurian ; 

 while in the Bassin de Namur and the Boulonnais the Stringo- 

 ■cephalus Beds at the summit of the Middle Devonian, succeeded 

 by the Upper Devonian, rested with a conglomeratic base on much 

 older rocks. 



He also alluded to the serious loss that geologists would suffer 

 from the substitution of the chisel-drill for the diamond-drill, 

 which appeared probable in borings for water and other purposes. 



Dr. H. Lapwokth said that the suggestion of the previous speaker, 

 that records of all British borings should be lodged at the Geological 

 Survey Office, was a good one ; but it would be necessary to carry 

 the matter a good deal farther than this, if the records were to be 

 •depended upon. The journals of borings were kept by men who 

 were often more or less uneducated, and possessed little or no 

 knowledge of geology. In his own experience he had found that 

 such records were not satisfactory. A Government control of boring 

 records could only be efficiently maintained if the Geological 

 Survey were notified before every boring was begun, in order that 

 the journal should be made under geological supervision. The 

 occasional use of the chisel in the process of boring was to be 

 regretted by geologists ; but the borer himself was concerned 

 solely with the cost, and in cases where cores are not demanded, 

 the chisel, being cheaper in many materials than the rotary pro- 

 cesses, was often largely employed. 



Mr. C. E. rJ. Bromehead remarked that, according to Messrs. Isler's 

 account, the Gault was divided into two parts, the upper 125 feet 

 [should be 121] being separated from the remainder by beds of 

 sand. The suggestion was that this sand was Upper Greensand, 

 and the upper part of the 'Gault' part of the Chalk. The total 

 thickness of Chalk then amounted to 700 feet [should be 702]. 

 It was most important that geologists should see the cores, and not 

 be dependent on the well-sinkers' accounts, which were a fruitful 

 cause of scientific immorality. On a priori grounds he would 

 have expected at least 700 feet of Chalk at Southall ; he therefore 

 interpreted Messrs. Isler's record in the light of a theory, and 

 quoted the resultant reading as evidence in support of that theory. 



